1. Field of the Invention
The present invention relates to a fusing apparatus for an image forming apparatus and a method thereof, which affix a toner image onto paper using a predetermined temperature and pressure. More particularly, the present invention relates to a fusing apparatus and method for securing rollers to corresponding housings when the housings expand due to the heat from the rollers.
2. Description of the Related Art
In electrophotographing image forming apparatuses such as a photocopier and a laser printer, a photoconductive medium such as a photoconductive drum is electrified by a charging unit which is adjacent to the photoconductive drum. An electrified surface of the photoconductive drum is exposed to a laser beam scanned by a laser scanning unit, in a pattern corresponding to a desired image, thereby forming an electrostatic latent image. A developing device supplies a toner to the photoconductive drum to develop the electrostatic latent image formed on the photoconductive drum into a toner image, that is, a visible image.
The visible image formed on the photoconductive drum is transferred to paper, after passing through a transfer medium. Alternatively, the visible image may be directly transferred to the printing paper without passing through the transfer medium.
The paper, to which the toner image is transferred, passes through a fusing apparatus, and accordingly, the toner image is affixed onto the paper. Paper passing through the fusing apparatus is discharged out of the image forming apparatus.
The fusing apparatus generally comprises a pressing roller and a heating roller which rotate in contact with each other. Referring to FIG. 1, the fusing apparatus comprises upper and lower housings 10 and 11 which include therein a pressing roller 13 and a heating roller 14 rotating in contact with each other. A heater 15 is mounted in the heating roller 14. One end of the heater 15 is arranged in such a manner that a first heater terminal 16 and a conductor member 17 are fastened by a first bolt 18 to the lower housing 11 altogether. The other end of the heater 15 is arranged in such a manner that a second heater terminal 21 and a connection piece 22 (see FIG. 2) are fastened by a second bolt 23 and supported by a sidewall 11a of the lower housing 11. The second bolt 23 is engaged with a nut 24 of which height ‘b’ is greater than thickness ‘a’ of the sidewall 11a. According to the above structure, although the thickness ‘a’ of the sidewall 11a decreases due to thermal expansion of the lower housing 11, fastening of the second heater terminal 21 and the connection piece 22 by the second bolt 23 can be maintained.
However, the conventional fusing apparatus as described above may lose stability when the lower housing 11 expands by heat as a whole, especially, in a horizontal direction. This is because, if the lower housing 11 horizontally expands, the heater 15 may be damaged or the heater terminals 16 and 21 are disconnected since the heater 15 and the heater terminals 16 and 21 are connected by welding.